yesterday, I decided to have my bettas switch tanks. Sadly my betta William didnt do too well with the plants in the tank he was put it, and his dorsal fin got torn. I immediantly switched them back. His fin is like torn into 3 different sections. He is still swimming normally.

What type of plants do you have in your tank? As for his fin, I would just add some aquarium salt to your tank, about 1/2 to 1 teaspoon per gallon every 24 to 48 hours, and probably do a full water change around the fourth day

Ok, yeah I would stay away from those plastic plants, but the ones with the rounded leaves seem to be fine though. Anyway, yeah aquarium salt is pretty cheap at wal mart, and it helps regenerate the fins and is a good disease preventative. Hope this works for you, and your betta gets better, the same thing happened to my betta, but it was with his filter.